4-Benzyloxymandelic acid (40.8 g) was dissolved in methanol (405 ml) and ethyl acetate (405 ml), and a solution of (S)-1-phenylethylamine (20.4 ml) in methanol (200 ml) and ethyl acetate (200 ml) was added to the solution. After the mixture was allowed to stand at room temperature, the resulting precipitates (37.9 g) were obtained. Recrystallization of the precipitates from methanol (926 ml) gave a salt of (S)-1-phenylethylamine and (S)-4-benzyloxymandelic acid (24.8 g) having a melting point of 174-180° C.
